There are universal components of life that make up the biomass of all known organisms. These include all proteinogenic amino acids, deoxy- and ribonucleotides, water and a range of metabolic cofactors. This test reports the amount of biomass precursors that have been reported to be essential constituents of the biomass equation. All of the following precursors need to be included in the biomass reaction to pass the test: Aminoacids: trp__L, cys__L, his__L, tyr__L, met__L, phe__L, ser__L, pro__L, asp__L, thr__L, gln__L, glu__L, ile__L, arg__L, lys__L, val__L, leu__L, ala__L, gly, asn__L DNA: datp, dctp, dttp, dgtp RNA: atp, ctp, utp, gtp Cofactors: nad, nadp, amet, fad, pydx5p, coa, thmpp, fmn and h2o These metabolites were selected based on the results presented by DOI:10.1016/j.ymben.2016.12.002 Please note, that the authors also suggest to count C1 carriers (derivatives of tetrahydrofolate(B9) or tetrahydromethanopterin) as universal cofactors. We have omitted these from this check because there are many individual compounds that classify as C1 carriers, and it is not clear a priori which one should be preferred. In a future update, we may consider identifying these using a chemical ontology. Implementation: Determine whether the model employs a lumped or split biomass reaction. Then, using an internal mapping table, try to identify the above list of essential precursors in list of precursor metabolites of either type of biomass reaction. List IDs in the models namespace if the metabolite exists, else use the MetaNetX namespace if the metabolite does not exist in the model. Identifies the cytosol from an internal mapping table, and assumes that all precursors exist in that compartment.

Biomass_Mextorquens_AM1_core lacks a total of 20 essential metabolites (24.39% of all biomass precursors). Specifically these are: ['MNXM94', 'cys__L_c', 'MNXM134', 'MNXM76', 'met__L_c', 'MNXM97', 'MNXM53', 'MNXM114', 'MNXM42', 'MNXM142', 'MNXM37', 'glu__L_c', 'MNXM231', 'MNXM70', 'MNXM78', 'MNXM199', 'MNXM140', 'ala__L_c', 'gly_c', 'MNXM147'].